Finding the Fourth Proportional to 31,078.34, 42,891.21 and 18,978.16

Step by Step Solution

1. Step 1: Write the proportion equation
   31,078.34 : 42,891.21 = 18,978.16 : x
2. Step 2: Convert to fraction form
   31,078.34/42,891.21 = 18,978.16/x
3. Step 3: Cross multiply
   31,078.34x = 42,891.21 × 18,978.16
4. Step 4: Simplify right side
   31,078.34x = 813,996,138.75
5. Step 5: Solve for x
   x = 813,996,138.75/31,078.34
6. Step 6: Final answer
   x = 26,191.75